A technology is known in which distance information is obtained from two images that are captured from different positions. In that technology, for example, images in which an object is captured are captured using two cameras installed at different positions. Moreover, from the two images, the correspondence relationship between the pixels having the same feature is obtained; and the distance to the object is obtained from the parallax amount and the positional relationship according to the principle of triangulation. As a result of calculating the distance with respect to all features, the distance information can be obtained from the two images.
However, in the conventional technology, there are times when the distance information cannot be obtained with a high degree of accuracy. For example, if a plurality of identical features is distributed on a straight line parallel to an epipolar plane, there is no difference among the features and thus the correspondence relationship becomes indeterminate. That makes it difficult to obtain the distance.